Questions are being asked of the stability of Oracle Team USA's race boat after the America's Cup defenders suffered their second capsize in the space of the month.

The latest mishap occurred when a high-speed foiling gybe went wrong during a training session on the Great Sound.

Oracle reported no crew were injured in the incident and only minimal damage was sustained to their 50-ft catamaran. While they escaped without any serious damage to their boat, the capsize - the latest in a series of training mishaps for the team - will be a concern for Oracle with racing set to start in just over two weeks.

Oracle are the only team to have capsized their race boat, pointing to potential problems with the boat's stability or the crew's technique in their maneuvers.

The incident occurred in breezy conditions of around 16-19 knots on the Great Sound, but still well within the range in which the yachts will be expected to perform in the regatta, which gets underway on May 27. The upper wind limit for the America's Cup is 24 knots.

The drama occurred as the team were trying to pull off a high-speed foiling gybe. As the team rolled through the gybe, the 50-ft catamaran kept turning and spun out, tipping onto its leeward hull. The four crew members in the leeward hull were forced to cling on while the hull became submerged.

The catamaran was swiftly righted and observers in Bermuda noted USA-17 returned to the team's base without obvious damage.

The team later issued a brief statement on their website: "Oracle Team USA capsized during a practice session focused on pre-start maneuvers.